Link between Melanoma & Breast Cancer

Last Modified: November 5, 2006

Dear OncoLink "Ask The Experts,"

I was diagnosed with malignant melanoma on my left wrist in June of 2005. Monday I had an OB-GYN appointment and a "lump" was found in my left breast. There is no history of breast cancer or melanoma in my family; however, there are numerous other types of cancer: colon, prostate and lung. Could the melanoma have anything to do with the possible development of breast cancer? I have not had further testing because I am afraid.

First and foremost, you should follow up on the imaging that was recommended by your OB-GYN. Although it may seem scary, once you have the imaging performed of your breast, you will have more information and therefore be able to make more informed decisions about the way in which you wish to proceed. Typically, a diagnostic mammogram or ultrasound is ordered to further evaluate the lump in your breast. These tests allow us to better determine what the lump in your breast might be. Pain is often associated with a cyst or an infection, and these could be detected through these imaging tests. If the imaging did reveal a lump that did not appear to be either a cyst or an infection, a biopsy might be done to identify what is causing that lump. Keep in mind that 80% of lumps that are biopsied turn out to be benign (not cancerous). In either case, getting that information will help you to make better decisions about the next step.

As far as a genetic link between the cancers you describe, it is unclear at this point. There are two types of genetic mutations that can occur within cells, both of which have the potential to be linked to certain types of cancer. The first is a mutation that occurs within the germ line; this occurs during development, and is present in all of the cells in a person's body. This type of mutation is passed on from a parent, and could be linked to a hereditary form of melanoma. The second is a mutation which happens to the somatic cells of the body (all cells except sperm and eggs); this type of mutation can also lead to cancer, but is not linked to hereditary forms of cancer.

There are several genes that have been identified as possible factors in hereditary melanoma. Further research is underway in this field to identify additional genes, as well as links to other conditions in persons possessing such mutations. Most of the laboratory studies to identify such mutations are performed within the context of a clinical trial. Hereditary or familial melanoma often occurs in patients and families with multiple abnormal moles, also called "dysplastic nevi". This is sometimes called familial atypical multiple mole melanoma (FAMMM). Melanoma is considered hereditary only if several immediate family members are affected. Mutations in the CDKN2A gene (also called p16 and MST1) are thought to account for approximately 25% of hereditary melanoma cases. Patients with such a mutation have a high risk of developing melanoma in their lifetimes. This mutation has also been linked to pancreatic cancer. Other genes that have been linked to melanoma include CDK4, and an area on Chromosome 1. Hereditary breast cancer has been linked to mutations within the BRCA1 or BRCA2 gene. Given the information you have provided, it would not appear that you are affected by these genetic abnormalities based on the scientific evidence available to us today.

However, I would strongly advise you to proceed with the radiologic testing to evaluate the breast lump ordered by your physician.